This document discusses rapid maxillary expansion (RME) and slow maxillary expansion techniques in orthodontics. It provides details on: - The history and development of RME, dating back to 1860 when E.M. Angell first achieved palatal expansion. - Indications for RME including posterior crossbites, Class III malocclusions, and narrow maxillary arches. - Effects of RME including separation of the mid-palatal suture, widening of the maxilla, tipping of posterior teeth, and downward rotation of the mandible. - Types of RME appliances including removable plates, tooth-borne expanders like Hyrax, and tooth/tissue

1. EXPANSION IN ORTHODONTICS
PROF (Dr.) SAIBEL FARISHTA

2. RAPID MAXILLARY EXPANSION (RME)
EXPANSION OF THE PALATE WAS FIRST ACHIEVED BY E.M. ANGELL IN 1860.
PALATAL EXPANSION CAN BE CARRIED OUT BY SLOW OR RAPID EXPANSIONS.
IT IS ALSO KNOWN AS RAPID PALATAL EXPANSION. IT IS A SKELETAL
TYPE OF EXPANSION THAT INVOLVES THE SEPARATION OF THE MID-
PALATAL SUTURE AND MOVEMENT OF THE MAXILLARY SHELVES AWAY
FROM EACH OTHER.
E.C. ANGELL IS CONSIDERED THE FATHER OF RME. IN 1860, HE USED A JACK
SCREW TYPE OF DEVICE BETWEEN MAXILLARY PREMOLARS IN A 14 YEAR OLD GIRL
CHILD AND ACHIEVED AN INCREASE IN ARCH WIDTH BY ¼th INCH IN 14 DAYS.
W. COFFIN IN 1877 INTRODUCED A SPRING CALLED COFFIN SPRING FOR THE
PURPOSE OF EXPANDING THE ARCH.
KORKHAUS AND HASS IN 1950’S REINTRODUCED RPE.

3. APPLIED ANATOMY
THE MAXILLA TOGETHER WITH THE PALATINE BONE FORMS THE HARD
PALATE, FLOOR AND GREATER PART OF THE LATERAL WALLS OF THE
NASAL CAVITY. THE MAXILLA IS A PAIRED BONE THAT ARTICULATES
WITH ITS OPPOSITE MEMBER AND VARIOUS OTHER BONES INCLUDING
FRONTAL, ETHMOID, NASAL, LACRIMAL, VOMER, ZYGOMATIC AND
PALATINE BONES. MOST OF THE SUTURAL ATTACHMENTS OF THE
MAXILLA TO THE ADJOINING BONES ARE AT ITS POSTERIOR AND
SUPERIOR ASPECTS LEAVING THE ANTERIOR AND INFERIOR ASPECTS
FREE, WHICH MAKES IT VULNERABLE FOR LATERAL DISPLACEMENT.
THE INTER-MAXILLARYAND THE INTER-PALATINE SUTURES ARE
COLLECTIVELY CALLED THE MID-PALATAL SUTURE.
RME SHOULD BE INITIATED PRIOR TO THE OSSIFICATION OF THE MID
PALATAL SUTURE.
VARIOUS STUDIES HAVE SUGGESTED A BROAD RANGE FOR OSSIFICATION
OF THE MID-PALATAL SUTURE [15 - 35 Yrs]

4. INDICATIONS FOR RME
1. POSTERIOR CROSS BITE WITH RELATIVE MAXILLARY DEFICIENCY.
A REAL MAXILLARY DEFICIENCY, ASSOCIATED WITH AN UNDERSIZED OR
NARROW MAXILLA.
RELATIVE MAXILLARY DEFICIENCY, CHARACTERIZED BY NORMAL MAXILLA
BUT OVERSIZED MANDIBLE.
2. CLASS III DENTAL OR SKELETAL MALOCCLUSIONS.
3. CLEFT PALATE PATIENTS HAVING A COLLAPSED MAXILLARY ARCH.
4. IN CASES WHICH REQUIRE FACE MASK THERAPY. RME IS USED ALONG WITH
FACE MASK TO LOOSEN THE MAXILLARY SUTURAL ATTACHMENTS TO
FACILITATE PROTRACTION.
5. MEDICAL PROBLEMS LIKE NASAL STENOSIS, POOR NASAL AIRWAY, DEVIATED
NASAL SEPTUM ETC.
DIAGNOSTIC AIDS
CASE HISTORY, CLINICAL EXAMINATION, STUDY MODELS, OCCLUSAL VIEW
RADIOGRAPHS, PA CEPHALOGRAM.

5. EFFECTS OF RME
THE MAXILLARY POSTERIOR TEETH ARE USED AS HANDLES TO APPLY A
TRANSVERSE RECIPROCAL FORCE SO AS TO OPEN THE MID-PALATAL SUTURE.
SINCE THE FORCE EMPLOYED FOR THE PROCEDURE IS VERY HIGH, NOT MUCH OF
ORTHODONTIC CHANGES ARE OBSERVED. THE APPLIANCE ON ACTIVATION,
COMPRESSES THE PERIODONTAL LIGAMENT AND BENDS THE ALVEOLAR
PROCESS BUCALLY AND SLOWLY OPENS THE MID-PALATAL SUTURE IN A FAN-
SHAPED OR TRIANGULAR MANNER, WITH MAXIMUM OPENING AT THE INCISOR
REGION AND SLOWLY DECREASING TOWARDS THE POSTERIOR PART OF PALATE.
THIS IS VISIBLE IN A POST RME OCCLUSAL RADIOGRAPH.
IN THE CORONAL PLANE, THE TWO HALVES OF THE MAXILLA ROTATE AWAY
FROM EACH OTHER. THE POINT AT WHICH THE ROTATION TAKES PLACE IS
AROUND THE FRONTO-MAXILLARY SUTURE.
IN THE SAGITTAL PLANE, THE MAXILLA IS ROTATED IN A DOWNWARD AND
FORWARD DIRECTION.
AMOUNT OF EXPANSION ACHIEVED
THE AMOUNT OF EXPANSION ACHIEVED IS UPTO 10 mm, 0.2 - 0.5 mm PER DAY

6. FAN SHAPED OPENING
OF THE MID-PALATAL SUTURE

7. EFFECT ON ALVEOLAR BONE
THE ALVEOLAR BONE IN THE AREAADJACENT TO ANCHOR TEETH BENDS
SLIGHTLY, DUE TO THE RESILIENT NATURE OF THE BONE.
EFFECT ON MAXILLARY ANTERIOR TEETH
THE APPEARANCE OF A MIDLINE SPACING BETWEEN THE TWO MAXILLARY
CENTRAL INCISORS IS THE MOST RELIABLE CLINICAL EVIDENCE OF THE
MAXILLARY SEPARATION.
EFFECT ON MAXILLARY POSTERIOR TEETH
THE MAXILLARY POSTERIOR TEETH ARE USED AS ANCHORS DURING RPE. THESE
TEETH SHOW BUCCAL TIPPING AND ALSO EXTRUDE TO A LIMITED EXTENT.
EFFECT ON MANDIBLE
A DOWNWARD AND BACKWARD ROTATION OF THE MANDIBLE IS SEEN
FOLLOWING RPE. THERE IS INCREASE IN THE MANDIBULAR PLANE ANGLE. THE
REASON FOR THIS IS THE EXTRUSION AND BUCCAL TIPPING OF THE MAXILLARY
MOLARS.

8. EFFECT ON ADJACENT CRANIAL BONES AND SUTURES
PARIETAL AND OCCIPITAL BONES ARE ALSO DISPLACED FOLLOWING RME.
NASAL EFFECTS OF RME
AFTER RME, THERE IS AN INCREASE IN INTRA-NASAL SPACE AS THE OUTER
WALLS OF NASAL CAVITY MOVES APART. THIS IS MAXIMUM IN INFERIOR
REGION OF THE NASAL CAVITY AND GRADUALLY DECREASES TOWARDS THE
SUPERIOR ASPECT. ALSO, THE NASAL BREATHING IS IMPROVED.
TYPES OF APPLIANCES USED
1. REMOVABLE APPLIANCES
2. FIXED APPLIANCES
• TOOTH BORNE
• TOOTH AND TISSUE BORN

9. 1. REMOVABLE APPLIANCES
IT CONSISTS OF A SPLIT ACRYLIC PLATE WITH A MIDLINE SCREW. THE
APPLIANCE IS RETAINED USING CLASPS ON THE POSTERIOR TEETH.
THE DISADVANTAGE OF REMOVABLE EXPANSION APPLIANCE IS THE
REQUIREMENT OF PATIENT COOPERATION AND THE DIFFICULTY IN RETAINING
THE PLATE INSIDE THE MOUTH.
2. FIXED APPLIANCES
THESE ARE MORE RELIABLE AND PRODUCE CONSISTENT SKELETAL EFFECTS
TOOTH AND TISSUE BORNE
1. DERICHSWELLER TYPE 2. HASS TYPE
TOOTH BORNE
1. ISAACSON TYPE 2. HYRAX TYPE
- TYPES -

10. TOOTH AND TISSUE BORNE
DERICHSWELLER TYPE –
THE FIRST PREMOLARS AND FIRST MOLARS ARE BANDED. WIRE TAGS ARE
SOLDERED ONTO THE PALATAL ASPECT OF THE BANDS. THESE WIRE TAGS GET
INSERTED INTO A SPLIT PALATAL ACRYLIC PLATE INCORPORATING A SCREW AT
IT’S CENTER.

11. THE FIRST PREMOLARS AND FIRST MOLARS ARE BANDED. A THICK STAINLESS
STEEL WIRE OF 1.2 MM IS SOLDERED ON THE BUCCAL AND LINGUAL ASPECTS
CONNECTING THE MOLAR AND PREMOLAR BANDS. THE LINGUAL WIRE IS KEPT
LONGER SO AS TO EXTEND PAST THE BAND ANTERIORLY AND POSTERIORLY.
THESE EXTENSIONS ARE BENT PALATALLY SO AS TO BE EMBEDDED IN THE
PALATAL ACRYLIC. THE SPLIT PALATAL ACRYLIC HAS A MIDLINE SCREW.
HASS TYPE -

12. TOOTH BORNE
ISAACSON TYPE -
IT IS A TOOTH BORNE APPLIANCE WHICH USES A SPRING LOADED SCREW
CALLED A ‘MINNE EXPANDER’.
THE FIRST MOLARS AND PREMOLARS ARE BANDED. METAL FLANGES ARE
SOLDERED ONTO THE BANDS ON THE BUCCAL AND LINGUAL SIDES. THE
EXPANDER CONSISTS OF A COIL SPRING HAVING A NUT WHICH CAN COMPRESS
THE SPRING. THE EXPANDER IS ACTIVATED BY CLOSING THE NUT SO THAT THE
SPRING GETS COMPRESSED.

13. HYRAX TYPE -
IT USES A SPECIAL TYPE OF SCREW CALLED THE HYRAX – HYGIENIC RAPID
EXPANDER. THE SCREWS HAVE HEAVY GAUGE WIRE EXTENSIONS THAT ARE
ADAPTED TO FOLLOW THE PALATAL CONTOUR AND ARE SOLDERED TO BANDS
ON MOLARS AND PRE-MOLARS.

14. TOOTH BORN RME APPLIANCE
[HYRAX]
TOOTH AND TISSUE BORN RME APPLIANCE
[HASS]

15. BONDED RME
A SPLINT COVERING VARIABLE NUMBER OF TEETH ON EITHER SIDE IS MADE
TO WHICH THE JACK SCREW IS ATTACHED. THEY CAN BE OF TWO TYPES –
1. CAST CAP SPLINTS - THESE ARE MADE OF SILVER – COPPER ALLOY
2. ACRYLIC SPLINTS - THESE ARE MADE OF POLYMETHYL METHACRYLATE. A
WIRE FRAMEWORK MAY BE ADAPTED AROUND THE TEETH TO REINFORCE
THE ACRYLIC. THESE SPLINTS ARE BONDED TO TEETH USING EITHER GLASS
IONOMER OR BONDING ADHESIVES.

16. DESCRIPTION OF A TYPICAL EXPANSION SCREW
IT CONSISTS OF AN OBLONG BODY DIVIDED INTO
TWO HALVES. EACH HALF HAS A THREADED
INNER SIDE THAT RECEIVES ONE END OF A
DOUBLE ENDED SCREW. THE SCREW HAS A
CENTRAL BLOSSING WITH FOUR HOLES. THESE
HOLES RECEIVE A KEY WHICH IS USED TO TURN
THE SCREW. TURNING SCREW BY 90 DEGREES
[1 TURN] BRINGS ABOUT A LINEAR MOVEMENT
OF 0.18 MM. THE PATTERN OF THREADING ON
EITHER SIDE IS OF OPPOSITE DIRECTION, THUS
TURNING THE SCREW WITHDRAWS IT FROM
BOTH SIDES SIMULTANEOUSLY.
ACTIVATION [TIMMS] – 90 DEGREE ROTATION IN
MORNING AND EVENING OF PATIENTS UPTO 15
YRS OLD AND 45 DEGREE ACTIVATION 4 TIMES A
DAY FOR PATIENTS OVER 15 YEARS OF AGE.
ACTIVATION [ZIMRING & ISSACSON] – IN YOUNG
GROWING PATIENTS 2 TURNS EACH DAY FOR 4-5
DAYS, LATER 1 PER DAY TILL THE REMAINING
EXPANSION IS ACHIEVED. IN ADULTS 2 TURNS
EACH DAY FOR FIRST 2 DAYS, 1 PER DAY FOR
NEXT 5-7 DAYS AND 1 EVERYALTERNATE DAY,
TILL THE DESIRED EXPANSION IS ACHIEVED.

17. CONTRAINDICATIONS OF RME
1. SINGLE TOOTH CROSSBITES
2. UNCO-OPERATIVE PATIENTS
3. USUALLY NOT CARRIED OUT AFTER OSSIFICATION OF MID-PALATAL
SUTURE
4. SKELETAL ASYMMETRY OF MAXILLAAND MANDIBLE
5. VERTICAL GROWERS WITH STEEP MANDIBULAR PLANE ANGLE
6. IN A PERIODONTICALLY WEAK DENTITION
RETENTION FOLLOWING RME
1. PALATAL OSTEOTOMY
2. LATERAL MAXILLARY OSTEOTOMY
3. ANTERIOR MAXILLARY OSTEOTOMY
SURGICALLY ASSISTED PALATAL EXPANSION
3 – 6 MONTHS OF RETENTION PERIOD IS REQUIRED FOLLOWING RME.
THE RME APPLIANCE ITSELF CAN BE USED FOR THE PURPOSE OF
RETENTION. THE SCREW SHOULD BE IMMOBILIZED USING COLD CURE
ACRYLIC. A FIXED OR A REMOVABLE RETAINER CAN ALSO BE USED.

18. SLOW EXPANSION
THE RESULTS ARE MORE STABLE WHEN THE MAXILLARY ARCH IS EXPANDED
SLOWLY AT THE RATE OF 0.5 – 1.0 mm PER WEEK. THE FORCES ARE IN THE RANGE
OF 2 – 4 POUNDS AS AGAINST 20 – 40 POUNDS GENERATED DURING RME. THE
EXPANSION LASTS FOR 2-5 MONTHS, AS AGAINST 1-2 WEEKS IN RME. SLOW
EXPANSION HAS BEEN TERMED DENTO-ALVEOLAR EXPANSION WITH SOME
SKELETAL CHANGES. [1 POUND = 450 Gms]
APPLIANCES USED FOR SLOW EXPANSION
1. JACK SCREW
2. COFFIN SPRING
3. QUAD HELIX
MILD ARCH EXPANSION AN BE ACHIEVED BY USING EXPANDED ARCHWIRES.
QUAD HELIX OR TRANSPALATAL ARCH CAN BE USED ALONG WITH FIXED
MECHANOTHERAPY.
ARCH EXPANSION USING FIXED APPLIANCES

19. JACK SCREW

20. COFFIN SPRING
IT IS A REMOVABLE
APPLIANCE CAPABLE
OF SLOW DENTO-
ALVEOLAR
EXPANSION. IT
CONSISTS OF AN
OMEGA SHAPED WIRE
OF 1.25 mm THICKNESS,
PLACED IN THE MID –
PALATAL REGION. THE
FREE ENDS OF THE
OMEGA WIRE ARE
EMBEDDED IN
ACRYLIC COVERING
THE SLOPES OF THE
PALATE. THE SPRING IS
ACTIVATED BY
PULLING THE TWO
SIDES APART
MANUALLY. IT CAN
ALSO BE ACTIVATED
BY USING THREE
PRONG PLIERS

21. IT HAS 4 HELICLES THAT INCREASE THE WIRE LENGTH. THEREFORE THE FLEXIBILITY
AND RANGE OF ACTION OF THIS APPLIANCE IS MORE. THE APPLIANCE IS
CONSTRUCTED USING 0.038 INCH WIRE AND IS SOLDERED TO BANDS ON THE FIRST
MOLARS. IT CONSISTS OF A PAIR OF ANTERIOR HELICLES AND A PAIR OF POSTERIOR
HELICLES. THE PORTION OF WIRE BETWEEN THE TWO ANTERIOR HELICLES IS CALLED
THE ANTERIOR BRIDGE. THE WIRE BETWEEN THE ANTERIOR AND POSTERIOR
HELICLES IS CALLED THE PALATAL BRIDGE. THE FREE WIRE ENDS ADJACENT TO THE
POSTERIOR HELICLES ARE CALLED OUTER ARMS. IT CAN BE PRE ACTIVATED BY
STRETCHING THE TWO MOLAR BANDS APART PRIOR TO CEMENTATION OR BY USING
THREE PRONG PLIERS AFTER CEMENTATION.
WHEN USED IN DECIDUOUS AND EARLY MIXED DENTITION PERIODS, A SKELETAL MID-
PALATAL SPLITTING CAN BE ACHIEVED.
QUAD HELIX

22. PRE EXPANSION POST EXPANSION

24. THANK YOU